I went to the trouble of burning a disc from the DVD to have a look before moving to 64bit gentoo. The installation went fine until the reboot, when it stopped with a grub error. Hurrah for ease-of-use! Now I have a coaster with ubuntu written on it.

Using the wife's laptop while gentoo compiles for a shiny new amd64...

It did not detect my video card (HP form of NVideo G Force 2MX) and came up at a screen resolution that obscured the bottom half of page and would not accept or go to any other resolution. As my (Hewlett Packard) HP Pavilion 1940 is a year 2000 buld I did not think it outdated for Linux.

I've never been able to get Ubuntu working on my machine either. Strangely, I can't get past the bit where you prepare the partitions on the hard disk, because it refuses to recognise the partitions that are already there, so I can't select the one I want to install on...

It is happening due to a problem talking to your network card or network. Does it unhang after a long period of time (say 10 minutes or so?). I am guessing you are using an onboard nforce2 chip which as far as I am aware has no known problems.
A BIOS update may fix the problem. Or disable the net chip, install, download the updated kernel (which has several net fixes), install it and switch the chip back on.